The present invention relates to a hinge mechanism designed to support the open-close cover of a vacuum-process apparatus for processing objects (e.g., liquid-crystal display (LCD) substrates and semiconductor wafers) and to enable the cover to rotate between an opened position and a closed position.
Generally, a vacuum-process apparatus for processing objects such as LCD substrates and semiconductor wafers comprises a load lock chamber and a process chamber. The load lock chamber has a transfer arm. The process chamber is located near the load lock chamber. A vacuum is maintained in both chambers. The transfer arm transfers objects, one by one, from the load lock chamber into the process chamber. In the process chamber, the objects are subjected to a specific process. The transfer arm transfers the objects, thus processed, from the process chamber back into the load lock chamber.
The process chamber comprises a main body (hereinafter referred to as "chamber body"). The chamber body has an inlet/outlet port made in one side. Through the inlet-outlet port, the objects are moved into and out of the process chamber. The process camber further comprises a gate valve and an air cylinder. The gate valve is located at the inlet/output port. The air cylinder is provided at said side of the chamber body, positioned above the gate valve and connected to the gate valve. The gate valve opens the inlet/outlet port when it is driven upwardly by the air cylinder, and closes the port when it is driven downwardly by the air cylinder.
The chamber body has a maintenance hole in the top. The maintenance hole can be opened and closed by a cover (hereinafter referred to as "open-close cover"). The open-close cover can rotate between an opened position and a closed position, supported by a hinge mechanism which is secured to the chamber body. The open-close cover usually closes the maintenance hole, thus maintaining vacuum in the process chamber. The interior of the process chamber needs to be cleaned periodically (for example, once or twice every month), and the heater provided in the process chamber must be replaced with a new one after a long use. The interior of the chamber cannot be cleaned or the heater cannot be replaced with a new one, without opening the maintenance hole. To open the maintenance hole, the hinge mechanism is operated, rotating the open-close cover upwardly to the opened position.
The hinge mechanism has one axle. The axle supports the open-close cover, which weighs as much as about 5 Kg. Being so heavy, the open-close cover may rotate downwardly, by accident, from the opened position to the closed position. In view of this, it is desired that the open-close cover be rotated by more than 90.degree., preferably about 100.degree., from the closed position to the opened position, thereby to open the maintenance hole. If the open-close cover is rotated through an angle greater than 90.degree., however, it will hang over the side of the chamber body, coming into interference with the air cylinder, which extends upward to a level above the top of the chamber body. This is because the gap between the chamber body and the hollow cylindrical cover protecting the chamber body is narrow, and the hinge mechanism is inevitably located near the air cylinder. Hence, the open-close cover cannot be rotated upwardly by more than 90.degree..